Bug 2566536 (CVE-2026-123876)

Summary: CVE-2026-123876 podman: containers-common: containers-common: default seccomp AF_VSOCK/NETLINK_AUDIT deny rules bypassable via 32-bit truncation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the default seccomp profile used by Podman via containers-common. Deny rules for AF_VSOCK and NETLINK_AUDIT compared socket arguments with unmasked 64-bit equality. Because the kernel truncates those int arguments to 32 bits, setting upper bits can bypass the deny rules.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2568387    
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Description OSIDB Bzimport 2026-11-03 21:59:57 UTC 
A flaw was found in containers-common (Podman/container-libs default seccomp profile). Deny rules for AF_VSOCK and NETLINK_AUDIT compared socket(2) integer arguments with unmasked 64-bit equality. On 64-bit architectures the kernel uses only the low 32 bits, so values such as AF_VSOCK|1<<32 bypass the deny rule while still creating the restricted socket type. This is confirmed in RHEL 9 and RHEL 10 containers-common seccomp.json. SELinux may still block some of these operations on enforcing hosts, but the seccomp profile itself does not enforce the intended restriction.